Euv lithography apparatus and operating method for mitigating contamination

ABSTRACT

An extreme ultra violet (EUV) lithography apparatus includes a light source that generates an EUV light beam, a scanner that receives the light from a junction with the light source and directs the light to a reticle stage, and a debris catcher disposed on a EUV beam path between the light source and the scanner. The debris catcher includes a network membrane including a plurality of nano-fibers.

BACKGROUND

One growing technique for semiconductor manufacturing is extremeultraviolet (EUV) lithography. EUV employs scanners using light in theEUV spectrum of electromagnetic radiation, including wavelengths fromabout one nanometer (nm) to about one hundred nm. Many EUV scannersstill utilize projection printing, similar to various earlier opticalscanners, except EUV scanners accomplish it with reflective rather thanrefractive optics, that is, with mirrors instead of lenses.

EUV lithography employs a laser-produced plasma (LPP), which emits EUVlight. The LPP is produced by focusing a high-power laser beam, from acarbon dioxide (CO₂) laser and the like, onto small fuel droplet targetsof tin (Sn) in order to transition it into a highly-ionized plasmastate. This LPP emits EUV light with a peak maximum emission of about13.5 nm or smaller. The EUV light is then collected by a collector andreflected by optics towards a lithography exposure object, such as asemiconductor wafer. Tin debris is generated in the process, whichdebris can adversely affect the performance and efficiency of the EUVapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1A is a diagram of a lithography apparatus in accordance with someembodiments.

FIG. 1B is a diagram of a source side and a scanner side in accordancewith some embodiments.

FIG. 1C is a diagram of laser and optics components in accordance withsome embodiments.

FIG. 2 is a diagram of a lithography apparatus in accordance with someembodiments of the present disclosure.

FIGS. 3A, 3B and 3C show diagrams of a debris catcher in accordance withsome embodiments of the present disclosure.

FIGS. 4A, 4B, 4C, 4D and 4F show diagrams of a debris catcher inaccordance with some embodiments of the present disclosure.

FIGS. 5A, 5B, 5C, 5D and 5E show diagrams of a debris catcher inaccordance with some embodiments of the present disclosure.

FIGS. 6A, 6B, 6C, 6D, 6E and 6F show various views of network membranesfor a debris catcher in accordance with embodiments of the presentdisclosure.

FIGS. 7A, 7B, 7C and 7D show various views of multiwall nanotubes inaccordance with embodiments of the present disclosure of the presentdisclosure.

FIGS. 8A, 8B and 8C show various views of network membranes for a debriscatcher in accordance with embodiments of the present disclosure.

FIG. 9A shows a manufacturing process of a network membrane, FIG. 9Bshows a flow chart thereof and FIG. 9C show manufacturing processes of anetwork membrane in accordance with an embodiment of the presentdisclosure.

FIGS. 10A and 10B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 11A and 11B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 12A and 12B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 13A and 13B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 14A and 14B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 15A and 15B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 16A and 16B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 17A and 17B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 18A and 18B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIGS. 19A and 19B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a debris catcher inaccordance with an embodiment of the present disclosure.

FIG. 20A and FIG. 20B are diagrams of a controller in accordance withsome embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus/device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein may likewise be interpreted accordingly. In addition, theterm “made of” may mean either “comprising” or “consisting of.” In thepresent disclosure, a phrase “one of A, B and C” means “A, B and/or C”(A, B, C, A and B, A and C, B and C, or A, B and C), and does not meanone element from A, one element from B and one element from C, unlessotherwise described.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the term “optic” is meant to be broadly construed toinclude, and not necessarily be limited to, one or more components whichreflect and/or transmit and/or operate on incident light, and includes,but is not limited to, one or more lenses, windows, filters, wedges,prisms, grisms, gratings, transmission fibers, etalons, diffusers,homogenizers, detectors and other instrument components, apertures,axicons and mirrors including multi-layer mirrors, near-normal incidencemirrors, grazing incidence mirrors, specular reflectors, diffusereflectors and combinations thereof. Moreover, unless otherwisespecified, the term “optic,” as used herein, is not meant to be limitedto components which operate solely within one or more specificwavelength range(s) such as at the EUV output light wavelength, theirradiation laser wavelength, a wavelength suitable for metrology or anyother specific wavelength.

In the present disclosure, the terms mask, photomask, and reticle areused interchangeably. In the present embodiment, the mask is areflective mask. One embodiment of the mask includes a substrate with asuitable material, such as a low thermal expansion material or fusedquartz. In various examples, the material includes TiO₂ doped SiO₂, orother suitable materials with low thermal expansion. The mask includesmultiple reflective layers deposited on the substrate. The multiplelayers include a plurality of film pairs, such as molybdenum-silicon(Mo/Si) film pairs (e.g., a layer of molybdenum above or below a layerof silicon in each film pair). Alternatively, the multiple layers mayinclude molybdenum-beryllium (Mo/Be) film pairs, or other suitablematerials that are configurable to highly reflect the EUV light. Themask may further include a capping layer, such as ruthenium (Ru),disposed on the ML for protection. The mask further includes anabsorption layer, such as a tantalum boron nitride (TaBN) layer,deposited over the multiple layers. The absorption layer is patterned todefine a layer of an integrated circuit (IC). Alternatively, anotherreflective layer may be deposited over the multiple layers and ispatterned to define a layer of an integrated circuit, thereby forming anEUV phase shift mask.

In the present embodiments, the semiconductor substrate is asemiconductor wafer, such as a silicon wafer or other type of wafer tobe patterned. The semiconductor substrate is coated with a resist layersensitive to the EUV light in the present embodiment. Various componentsincluding those described above are integrated together and are operableto perform various lithography exposing processes. The lithographysystem may further include other modules or be integrated with (or becoupled with) other modules.

A lithography system is essentially a light projection system. Light isprojected through a ‘mask’ or ‘reticle’ that constitutes a blueprint ofthe pattern that will be printed on a workpiece. The blueprint is fourtimes larger than the intended pattern on the wafer or chip. With thepattern encoded in the light, the system's optics shrink and focus thepattern onto a photosensitive silicon wafer. After the pattern isprinted, the system moves the wafer slightly and makes another copy onthe wafer. This process is repeated until the wafer is covered inpatterns, completing one layer of the eventual semiconductor device. Tomake an entire microchip, this process will be repeated one hundredtimes or more in some embodiments, laying patterns on top of patterns.The size of the features to be printed varies depending on the layer,which means that different types of lithography systems are used fordifferent layers, from the latest-generation EUV systems for thesmallest features to older deep ultraviolet (DUV) systems for thelargest.

FIG. 1A is a schematic and diagrammatic view of an EUV lithographysystem 10. The EUV lithography system 10 includes an EUV radiationsource apparatus 100 (sometimes referred to herein as a “source side” inreference to it or one or more of its relevant parts) to generate EUVlight, an exposure tool 300, such as a scanner, and an excitation lasersource apparatus 200. As shown in FIG. 1A, in some embodiments, the EUVradiation source apparatus 100 and the exposure tool 300 are installedon a main floor (MF) of a clean room, while the excitation laser sourceapparatus 200 is installed in a base floor (BF) located under the mainfloor. Each of the EUV radiation source apparatus 100 and the exposuretool 300 are placed over pedestal plates PP1 and PP2 via dampers DP1 andDP2, respectively. The EUV radiation source apparatus 100 and theexposure tool 300 are coupled to each other at a junction 330 by acoupling mechanism, which may include a focusing unit (not shown).

The EUV lithography system 10 is designed to expose a resist layer toEUV light (or EUV radiation). The resist layer is a material sensitiveto the EUV light. The EUV lithography system 10 employs the EUVradiation source apparatus 100 to generate EUV light having a wavelengthranging between about 1 nanometer (nm) and about 100 nm. In oneparticular example, the EUV radiation source apparatus 100 generates EUVlight with a wavelength centered at about 13.5 nm. In variousembodiments, the EUV radiation source apparatus 100 utilizes LPP togenerate the EUV radiation.

As shown in FIG. 1A, the EUV radiation source apparatus 100 includes atarget droplet generator 115 and an LPP collector 110, enclosed by achamber 105. The target droplet generator 115 generates a plurality oftarget droplets 116. In some embodiments, the target droplets 116 aretin (Sn) droplets. In some embodiments, the target droplets 116 have adiameter of about 30 microns (μm). In some embodiments, the targetdroplets 116 are generated at a rate about fifty droplets per second andare introduced into an excitation zone 106 at a speed of about seventymeters per second (m/s or mps). Other material can also be used for thetarget droplets 116, for example, a liquid material such as a eutecticalloy containing Sn and lithium (Li).

As the target droplets 116 move through the excitation zone 106,pre-pulses (not shown) of the laser light first heat the target droplets116 and transform them into lower-density target plumes. Then, the mainpulse 232 of laser light is directed through windows or lenses (notshown) into the excitation zone 106 to transform the target plumes intoa LPP. The windows or lenses are composed of a suitable materialsubstantially transparent to the pre-pulses and the main pulse 232 ofthe laser. The generation of the pre-pulses and the main pulse 232 issynchronized with the generation of the target droplets 116. In variousembodiments, the pre-heat laser pulses have a spot size about 100 μm orless, and the main laser pulses have a spot size about 200-300 μm. Adelay between the pre-pulse and the main pulse 232 is controlled toallow the target plume to form and to expand to an optimal size andgeometry. When the main pulse 232 heats the target plume, ahigh-temperature LPP is generated. The LPP emits EUV radiation, which iscollected by one or more mirrors of the LPP collector 110. Moreparticularly, the LPP collector 110 has a reflection surface thatreflects and focuses the EUV radiation for the lithography exposingprocesses. In some embodiments, a droplet catcher 120 is installedopposite the target droplet generator 115. The droplet catcher 120 isused for catching excess target droplets 116 for example, when one ormore target droplets 116 are purposely or otherwise missed by thepre-pulses or main pulse 232.

As shown the target droplet generator 115 generates tin droplets along avertical axis. Each droplet is hit by a CO₂ laser pre-pulse (PP). Thedroplet will responsively change its shape into a “pancake” duringtravel along the axial direction. After a time duration (MP to PP delaytime), the pancake is hit by a CO₂ laser main (MP) proximate to aprimary focus (PF) in order to generate an EUV light pulse. The EUVlight pulse is then collected by an LPP collector 100 and delivered tothe scanner side for use in wafer exposure.

The LPP collector 110 includes a proper coating material and shape tofunction as a mirror for EUV collection, reflection, and focusing. Insome embodiments, the LPP collector 110 is designed to have anellipsoidal geometry. In some embodiments, the coating material of thecollector 100 is similar to the reflective multilayer of an EUV mask. Insome examples, the coating material of the LPP collector 110 includesmultiple layers, such as a plurality of molybdenum/silicon (Mo/Si) filmpairs, and may further include a capping layer (such as ruthenium (Ru))coated on the multiple layers to substantially reflect the EUV light.

The main pulse 232 is generated by the excitation laser source apparatus200. In some embodiments, the excitation laser source apparatus 200includes a pre-heat laser and a main laser. The pre-heat laser generatesthe pre-pulse that is used to heat or pre-heat the target droplet 116 inorder to create a low-density target plume, which is subsequently heated(or reheated) by the main pulse 232, thereby generating increasedemission of EUV light.

The excitation laser source apparatus 200 may include a laser generator210, laser guide optics 220 and a focusing apparatus 230. In someembodiments, the laser generator 210 includes a carbon dioxide (CO₂)laser source or a neodymium-doped yttrium aluminum garnet (Nd:YAG) lasersource. The laser light 231 generated by the laser generator 210 isguided by the laser guide optics 220 and focused into the main pulse 232of the excitation laser by the focusing apparatus 230, and thenintroduced into the EUV radiation source apparatus 100 through one ormore apertures, such as the aforementioned windows or lenses,

In such an EUV radiation source apparatus 100, the LPP generated by themain pulse 232 creates physical debris, such as ions, gases and atoms ofthe droplet 116, along with the desired EUV light. In operation of thelithography system 10, there is an accumulation of such debris on theLPP collector 110, and such physical debris exits the chamber 105 andenters the exposure tool 300 (i.e., the “scanner side”) as well as theexcitation laser source apparatus 200.

In various embodiments, a buffer gas is supplied from a first buffer gassupply 130 through the aperture in the LPP collector 110 by which themain pulse 232 of laser light is delivered to the tin droplets 116. Insome embodiments, the buffer gas is hydrogen (H₂), helium (He), argon(Ar), nitrogen (N₂), or another inert gas. In certain embodiments, H₂ isused, since H radicals generated by ionization of the buffer gas canalso be used for cleaning purposes. Furthermore, H₂ absorbs the leastamount of EUV light produced by the source side, and thus absorbs theleast light used by the semiconductor manufacturing operations performedin the scanner side of the lithography apparatus 10. The buffer gas canalso be provided through one or more second buffer gas supplies 135toward the LPP collector 110 and/or around the edges of the LPPcollector 110. Further, and as described in more detail later below, thechamber 105 includes one or more gas outlets 140 so that the buffer gasis exhausted outside the chamber 105.

Hydrogen gas has low absorption of the EUV radiation. Hydrogen gasreaching to the coating surface of the LPP collector 110 reactschemically with a metal of the target droplet 116, thus forming ahydride, e.g., metal hydride. When Sn is used as the target droplet 116,stannane (SnH₄), which is a gaseous byproduct of the EUV generationprocess, is formed. The gaseous SnH₄ is then pumped out through theoutlet 140. However, it is difficult to exhaust all gaseous SnH₄ fromthe chamber and to prevent the Sn debris and SnH₄ from entering theexposure tool 300 and the excitation laser source apparatus 200. To trapthe Sn, SnH₄ or other debris, one or more debris collection mechanismsor devices 150 are employed in the chamber 105. In various embodiments,a controller 350 controls the EUV lithography system 10 and/or one ormore of its components shown in and described above with respect to FIG.1A.

A large amount of Sn debris at high speed will be generated during EUVexposure. Most of the Sn debris will be carried out by a scrubber inconjunction with a high density H₂ flow. However, a portion of the Snparticles will evade the H₂ flow protection and reach the interfacebetween source and scanner chambers. Then, Sn particles will beaccelerated by a large pressure delta toward the reticle in variousembodiments.

As shown in FIG. 1B, the exposure tool 300 (sometimes referred to hereinas the “scanner side” in reference to it or one or more of its relevantparts) includes various reflective optic components, such asconvex/concave/flat mirrors, a mask holding mechanism 310 including amask stage (i.e., a reticle stage), and wafer holding mechanism 320. TheEUV radiation generated by the EUV radiation source apparatus 100 andfocused at intermediate focus 160 is guided by the reflective opticalcomponents 305 onto a mask (not shown) secured on the reticle stage 310,also referenced as a mask stage herein. In some embodiments, thedistance from the intermediate focus 160 and the reticle disposed in thescanner side is approximately 2 meters. In some embodiments, a lowercone is provided at or near the intermediate focus 160 so that the EUVlight pass through an inlet opening and an outlet opening of the cone.

In some embodiments, the reticle size is approximately 152 mm by 152 mm.In some embodiments, the reticle stage 310 includes an electrostaticchuck, or ‘e-chuck,’ (not shown) to secure the mask. The EUV lightpatterned by the mask is used to process a wafer supported on waferstage 320. Because gas molecules absorb EUV light, the chambers andareas of the lithography system 10 used for EUV lithography patterningare maintained in a vacuum or a low-pressure environment to avoid EUVintensity loss. In various embodiments, the controller 350 controls oneor more of the components of the EUV lithography system 10 as shown inand described with respect to FIG. 1B.

FIG. 1C shows further detail of the chamber 105 of the EUV radiationsource apparatus 100, in which the relation of the LPP collector 110,the buffer gas supply 130, the second buffer gas supply 135, the gasoutlet ports 140 and the intermediate focus 160 are illustrated. Themain pulse 232 of the laser light is directed through the LPP collector110 to the excitation zone 106 where it irradiates a target plume toform an LPP. The LPP emits EUV light that is collected by the LPPcollector 110 and then directed through the intermediate focus 160toward the exposure tool 300 for use in patterning a wafer as describedpreviously. In various embodiments, the controller 350 controls one ormore of the components of the EUV lithography system 10 as shown in anddescribed with respect to FIG. 1C.

In various embodiments of the EUV lithography system 10, pressure in theLPP source side is higher than pressure in the scanner side. This isbecause the source side uses hydrogen gas to force the removal ofairborne Sn debris therefrom, while the scanner side is maintained innear vacuum in order to avoid diminishing strength of the EUV light(being absorbed by air molecules) or otherwise interfering with thesemiconductor manufacturing operations performed therein. In variousembodiments, the intermediate focus 160 is disposed at a junction 330 orintersection of the source side and the scanner side.

As EUV light or radiation is generated, at least 50% of the mass of eachtin droplet used to form the LPP does not vaporize, but instead becomesnumerous tin nanoparticles ranging in diameter from 30 nm to 100 nm.Detrimentally, the nanoparticles also flow from the source side toscanner side through the intermediate focus 160 in the same generaldirection as the light generated by the source side. In someembodiments, tin debris form gaseous SnH_(x), which flows into thescanner side and may reduced to Sn at some surfaces of the scanner.

Embodiments of the present disclosure prevent tin debris (e.g.,nanoparticles and/or gaseous SnH_(x)) from flying into the scanner fromthe LPP radiation source by using a debris catcher which has a high EUVtransmittance, e.g., more than about 92.5%.

FIG. 2 is a diagram of an EUV lithography system in accordance with someembodiments. As shown in FIG. 2 , a debris catcher 500 is disposedbetween the outlet opening of the lower cone (intermediate focus cone)400 of the LPP radiation source and an entrance opening 410 of the EUVoptics chamber of the scanner. The debris catcher 500 is configured tocollect tin debris generated in the LPP radiation source and/or toprevent the tin debris from flowing into the scanner.

In some embodiments, a distance between the outlet opening of the cone400 and the debris catcher 500 is in a range from about 1 mm to about 2cm, and a distance between the debris catcher and the entrance opening410 of the EUV optics chamber is in a range from about 1 mm to about 2cm.

In some embodiments, the debris catcher 500 includes a network membraneincluding a plurality of fibers as explained below. In some embodiments,an EUV transmittance of the network membrane is more than about 95%.

FIGS. 3A, 3B and 3C show diagrams of a debris catcher in accordance withsome embodiments of the present disclosure.

In some embodiments, the debris catcher 500 is a revolver type havingmultiple slots as shown in FIG. 3A. A revolver plate 501 is configuredto rotate around the rotational axis 502 to switch from one slot toanother slot by using a motor or any other suitable rotationalmechanism. One or more of the slots have a network membrane 510 fullycovering the opening of the slot. Each slot corresponds to the openingof the outlet port of the cone 400. In some embodiments, a size of theslot and/or the network membrane is greater than the size of the openingof the outlet port of the cone 400 and the entrance opening 410 of theoptics chamber. In some embodiments, the diameter of the slot or thenetwork membrane 510 is in a range from about 2 cm to about 5 cm. Insome embodiments, at least one slot 510E has no membrane and thus is athrough opening. In some embodiments, the number of the slots 521 is 3,4, 5, 6, 7 or 8 or any number from 9-16.

In some embodiments, the debris catcher 500 is a fan-shaped switcher asshown in FIG. 3B. In some embodiments, one or more network membranes 510each supported by a frame 509 are attached to the center rotationalmechanism 530 via an arm 508. In some embodiments, the debris catcher500 includes at least one open frame having no membrane (i.e., a throughopening 510E), as shown in FIG. 3B. In some embodiments, the number ofthe frames is 3, 4, 5, 6, 7 or 8 or any number from 9-16. The rotationalmechanism 530 includes a motor and one or more gears to rotate the armsaround the rotational axis in a step-by-step manner. In someembodiments, a size of the frame 509 and/or the network membrane 510 isgreater than the size of the opening of the outlet port of the cone 400and the entrance opening 410 of the optics chamber. In some embodiments,the diameter of the frame or the network membrane is in a range fromabout 2 cm to about 5 cm.

In some embodiments, the debris catcher 500 has a rectangular plate(tape) shape having one or more slots as shown in FIG. 3C. Therectangular plate 501 is configured to slide along its longitudinaldirection to switch one slot to another slot by using a motor or anyother suitable sliding mechanism. One or more of the slots have anetwork membrane 510 to fully cover the opening of the slot. Each slotcorresponds to the opening of the outlet port of the cone 400. In someembodiments, a size of the slot and/or the network membrane is greaterthan the size of the opening of the outlet port of the cone 400 and theentrance opening of the optics chamber. In some embodiments, when theslot is circular, the diameter of the slot or the network membrane is ina range from about 2 cm to about 5 cm. In some embodiments, when theslot is rectangular (square), the sides of the slot or the networkmembrane is in a range from about 2 cm to about 5 cm. In someembodiments, at least one slot has no membrane, and thus, is a throughopening. In some embodiments, the number of the slots is 3, 4, 5, 6, 7or 8 or any number from 9-16.

In some embodiments, the debris catcher 500 is configured to switch fromone slot or frame having the network membrane to another slot or framehaving the network membrane according to a switching signal from acontroller 350 (see, FIG. 1A). In some embodiments, when the EUVtransmittance is or is estimated to be less than about 90%, theswitching of the network membrane is performed. In some embodiments, theswitching signal is provided periodically, for example, every day, weekor month, which may indicate EUV transmission degradation. In otherembodiments, the switching signal is provided every certain number ofpulses of the excitation laser, which may indicate EUV transmissiondegradation. In some embodiments, the switching signal is provided whenan intensity of the EUV radiation in the scanner side (or in the LPPradiation side) decreases below a threshold. In some embodiments, aweight monitor 411 (see, FIG. 2 ) is provided inside or near the lowercone 400 to monitor a weight of the accumulated Sn, and when the amountof Sn exceeds a threshold, which may indicate EUV transmissiondegradation, the switching signal is provided.

FIG. 4A shows a cross sectional view of the network membrane 550. Insome embodiments, a frame 555 is provided one or both sides of thenetwork membrane. In some embodiments, the frame 555 corresponds to theframe 509 of FIG. 3B, or is a part of the revolver plate 501 of FIG. 3Aand a plate 501 of FIG. 3C.

In some embodiments, the frame 555 is formed of one or more layers ofcrystalline silicon, polysilicon, silicon oxide, silicon nitride, aceramic, a metal or an organic material (e.g., resin).

In some embodiments, the frame 555 has a circular opening 557 and acircular outer periphery as shown in FIG. 4B. In some embodiments, theframe 555 has a circular opening 557 and a rectangular (e.g., a square)outer periphery as shown in FIG. 4C. In some embodiments, the frame 555has a rectangular (e.g., square) opening 557 and a rectangular (e.g.,square) outer periphery as shown in FIG. 4D. In some embodiments, theframe 555 has a rectangular (e.g., square) opening 557 and a circularouter periphery as shown in FIG. 4E. The network membrane 550 has acircular shape, a rectangular (e.g., square) shape or any otherpolygonal shape and is disposed over the frame 555 to fully cover theopening 557.

In some embodiments, a first cover sheet (or layer) 520 is formed at thebottom surface of the network membrane 550 between the frame 555 and thenetwork membrane 550 as shown in FIG. 5A. In some embodiments, a secondcover sheet 530 is formed over the network membrane 550 to seal thenetwork membrane together with the first cover sheet 520, as shown inFIG. 5B. In some embodiments, no first cover sheet is used and only thesecond cover sheet 530 is used as show in FIG. 5C. In some embodiments,a third cover sheet 540 covers the entire structure of FIG. 5B (or FIG.5A or 5C), as shown in FIG. 5D. In some embodiment, no first cover sheetand/or second cover sheet are used as shown in FIG. 5E. In someembodiments, the material of third cover sheet 540 of FIG. 5E is thesame as the material of the first and/or second cover sheets.

In some embodiments, one of or both of the first cover layer 520 and thesecond cover layer 530 include a two-dimensional material in which oneor more two-dimensional layers are stacked. Here, a “two-dimensional”layer refers to one or a few crystalline layers of an atomic matrix or anetwork having thickness within the range of about 0.1-5 nm, in someembodiments.

In some embodiments, the two-dimensional materials of the first coverlayer 520 and the second cover layer 530 are the same or different fromeach other. In some embodiments, the first cover layer 520 includes afirst two-dimensional material and the second cover layer 530 includes asecond two-dimensional material.

In some embodiments, the two-dimensional material for the first coverlayer 520 and/or the second cover layer 530 includes at least one ofboron nitride (BN), graphene, and/or transition metal dichalcogenides(TMDs), represented by MX₂, where M=Mo, W, Pd, Pt, and/or Hf, and X=S,Se and/or Te. In some embodiments, a TMD is one of MoS₂, MoSe₂, WS₂ orWSe₂.

In some embodiments, a total thickness of each of the first cover layer520 and the second cover layer 530 is in a range from about 0.3 nm toabout 3 nm and is in a range from about 0.5 nm to about 1.5 nm in otherembodiments. In some embodiments, a number of the two-dimensional layersof each of the two-dimensional materials of the first and/or secondcover layers is 1 to about 20, and is 2 to about 10 in otherembodiments. When the thickness and/or the number of layers is greaterthan these ranges, EUV transmittance of the debris catcher may bedecreased and when the thickness and/or the number of layers is smallerthan these ranges, mechanical strength of the debris catcher may beinsufficient.

In some embodiments, a third cover layer 540 includes at least one layerof an oxide, such as HfO₂, Al₂O₃, ZrO₂, Y₂O₃, or La2O3. In someembodiments, the third cover layer 540 includes at least one layer ofnon-oxide compounds, such as B₄C, YN, Si₃N₄, BN, NbN, RuNb, YF₃, TiN, orZrN. In some embodiments, the protection layer 40 includes at least onemetal layer made of, for example, Ru, Nb, Y, Sc, Ni, Mo, W, Pt, or Bi.In some embodiments, the third cover layer 540 is a single layer, and inother embodiments, two or more layers of these materials are used as theprotection layer 40. In some embodiments, a thickness of the protectionlayer is in a range from about 0.1 nm to about 5 nm, and is in a rangefrom about 0.2 nm to about 2.0 nm in other embodiments. When thethickness of the third cover layer 540 is greater than these ranges, EUVtransmittance of the debris catcher may be decreased and when thethickness of the third cover layer 540 is smaller than these ranges, themechanical strength of the debris catcher may be insufficient.

In some embodiments, the thickness of the network membrane 550 is in arange from about 5 nm to about 100 nm, and is in a range from about 10nm to about 50 nm in other embodiments. When the thickness of thenetwork membrane 550 is greater than these ranges, EUV transmittance ofthe debris catcher may be decreased and when the thickness of thenetwork membrane 550 is smaller than these ranges, the mechanicalstrength of the debris catcher may be insufficient.

FIGS. 6A, 6B, 6C, 6D, 6E and 6F show various views of network membranesfor a debris catcher in accordance with embodiments of the presentdisclosure.

In some embodiments, the network membrane 550 includes a plurality ofnanotubes. In some embodiments, the plurality of nanotubes are randomlyarranged to form a network structure. In some embodiments, a diameter ofeach of the plurality of nanotubes is in a range from about 0.5 nm toabout 20 nm and is in a range from about 1 nm to about 10 nm in otherembodiments. In some embodiments, a length of each of the plurality ofnanotubes is in a range from about 0.5 μm to about 50 μm and is in arange from about 1.0 μm to about 20 μm in other embodiments.

In some embodiments, the plurality of nanotubes are carbon nanotubes,boron nitride nanotubes, and/or TMD nanotubes, where TMD is representedby MX₂, where M=Mo, W, Pd, Pt, and/or Hf, and X=S, Se and/or Te. In someembodiments, the plurality of nanotubes are MoS₂ nanotubes, MoSe₂nanotubes, WS₂ nanotubes or WSe₂ nanotubes.

In some embodiments, the plurality of nanotubes include only one type ofnanotubes in terms of material and structure. In some embodiments, theplurality of nanotubes include nanotubes of the same material. In someembodiments, the network membrane 550 only includes single wallnanotubes 511 as shown in FIG. 6A. In other embodiments, the networkmembrane 550 only includes multiwall (e.g., double wall) nanotubes 513as shown in FIG. 6B. A multiwall nanotube includes an inner tube and oneor more outer tubes coaxially disposed around the inner tube. In someembodiments, the outer tube is movable along the axial direction withrespect to the inner tube and in other embodiments, the outer tube isfixed on the outer surface of the inner tube. In some embodiments, adiameter of each of the single wall nanotubes is in a range from about0.5 nm to about 5 nm and is in a range from about 1 nm to about 2 nm inother embodiments. In some embodiments, a diameter of each of themultiwall nanotubes is in a range from about 3 nm to about 20 nm and isin a range from about 5 nm to about 10 nm in other embodiments.

In some embodiments, the plurality of nanotubes include two or moretypes of nanotubes in terms of material and structure. In someembodiments, the plurality of nanotubes include single wall nanotubesmade of two or more materials (mixture of different material nanotubes).For example, in some embodiments, the plurality of nanotubes include aplurality of first nanotubes and a plurality of second nanotubes made ofdifferent material from the plurality of first nanotubes, and both ofthem are single wall nanotubes.

In some embodiments, the main network layer 550 includes a plurality ofnanotubes 511 which are single wall nanotubes, and a plurality ofnanotubes 513 which are multiwall (e.g., double wall) nanotubes as shownin FIG. 6C. In some embodiments, an amount (weight) of the single wallnanotubes 511 is greater than an amount of the multiwall nanotubes 513.In some embodiments, an amount (weight) of the single wall nanotubes 511is greater than an amount of the multiwall nanotubes 513.

In some embodiments, the plurality of single wall nanotubes 511 are madeof a same material as the plurality of multiwall nanotubes 513. Forexample, the plurality of single wall nanotubes 511 are single wallcarbon nanotubes, and the plurality of multiwall nanotubes 513 aremultiwall carbon nanotubes. In other embodiments, the plurality ofsingle wall nanotubes 511 are made of a different material from theplurality of multiwall nanotubes 513. For example, the plurality ofsingle wall nanotubes 511 are single wall TMD nanotubes, and theplurality of multiwall nanotubes 513 are multiwall carbon nanotubes. Insome embodiments, the plurality of nanotubes are multiple nanotubes madeof two or more different materials (mixture of two types of multiwallnanotubes).

In some embodiments, the main network membrane 550 includes a pluralityof nanotubes 511 and a plurality of flakes 521 (nano-flakes) made of atwo-dimensional material in which one or more two-dimensional layers arestacked, as shown in FIGS. 6D-6F.

In some embodiments, the two-dimensional material flakes 521 include atleast one of boron nitride (BN), graphene, and/or transition metaldichalcogenides (TMDs), represented by MX₂, where M=Mo, W, Pd, Pt,and/or Hf, and X=S, Se and/or Te. In some embodiments, a TMD is one ofMoS₂, MoSe₂, WS₂ or WSe₂.

In some embodiments, a thickness of two-dimensional material flakes 521is in a range from about 0.3 nm to about 3 nm and is in a range fromabout 0.5 nm to about 1.5 nm in other embodiments. In some embodiments,a number of the two-dimensional layers of two-dimensional materialflakes 521 is 1 to about 20, and is 2 to about 10 in other embodiments.When the thickness and/or the number of layers is greater than theseranges, EUV transmittance of the debris catcher may be decreased andwhen the thickness and/or the number of layers is smaller than theseranges, mechanical strength of the debris catcher may be insufficient.

In some embodiments, the shape of the two-dimensional material flakes521 is random. In other embodiments, the shape of the two-dimensionalmaterial flakes 521 is triangular or hexagonal. In certain embodiments,the shape of the two-dimensional material flakes 521 is a triangleformed by three atoms or a hexagon formed by six atoms. In someembodiments, a size (area) of each of the two-dimensional materialflakes 521 is in a range from about 10 nm² to about 10 μm² and is in arange from about 100 nm² to about 1 μm² in other embodiments.

In some embodiments, the two-dimensional material flakes 521 areembedded in or mixed with a plurality of single wall nanotubes 511 asshown in FIG. 6D. In some embodiments, the two-dimensional materialflakes 521 are embedded in or mixed with a plurality of multiwallnanotubes 513 as shown in FIG. 6E. In some embodiments, thetwo-dimensional material flakes 521 are embedded in or mixed with aplurality of single wall nanotubes 511 and a plurality of multiwallnanotubes 513, as shown in FIG. 6F.

In some embodiments, an amount (weight) of the two-dimensional materialflakes 521 is in a range from about 5% to about 30% with respect to atotal weight of the network membrane 550, and is in a range from about10% to about 20% in other embodiments. When the amount oftwo-dimensional material flakes is greater than these ranges, the EUVtransmittance of the debris catcher may be decreased and when the amountof two-dimensional material flakes is smaller than these ranges, themechanical strength of the debris catcher may be insufficient.

FIGS. 7A, 7B, 7C and 7D show various views of multiwall nanotubes inaccordance with embodiments of the present disclosure of the presentdisclosure. In some embodiments, the multiwall nanotubes are alsoreferred to as co-axial nanotubes.

FIG. 7A shows a perspective view of a multiwall co-axial nanotube 560having three tubes 562, 564 and 566 and FIG. 7B shows a cross sectionalview thereof. In some embodiments, the inner tube 562 is a carbonnanotube, and two outer tubes 564 and 566 are boron nitride nanotubes.

The number of tubes of the multiwall nanotubes is not limited to three.In some embodiments, the multiwall nanotube has two co-axial nanotubesas shown in FIG. 7C, and in other embodiments, the multiwall nanotubeincludes the innermost tube 562 and the first to N-th nanotubesincluding the outermost tube 562N, where N is a natural number from 1 toabout 20, as shown in FIG. 7D. In some embodiments, N is up to 10 or upto 5. In some embodiments, at least one of the first to the N-th outerlayers is a nanotube coaxially surrounding the innermost nanotube 562.In some embodiments, two of the innermost nanotubes 562 and the first tothe N-th outer layers 562, 564, . . . 562N are made of differentmaterials from each other. In some embodiments, N is at least two (i.e.,three or more tubes), and two of the innermost nanotubes 563 and thefirst to the N-th outer tubes 564, 566, . . . 562N are made of the samematerials. In other embodiments, three of the innermost nanotubes 562and the first to the N-th outer tubes 564, 566, . . . 562N are made ofdifferent materials from each other.

In some embodiments, each of the nanotubes of the multiwall nanotube isone selected from the group consisting of a carbon nanotube, a boronnitride nanotube, a transition metal dichalcogenide (TMD) nanotube,where TMD is represented by MX₂, where M is one or more of Mo, W, Pd,Pt, or Hf, and X is one or more of S, Se or Te. In some embodiments, atleast two of the tubes of the multiwall nanotube are made of differentmaterial from each other. In some embodiments, adjacent two layers(tubes) of the multiwall nanotube are made of different material fromeach other.

In some embodiments, the multiwall nanotube includes three co-axiallylayered tubes made of different materials from each other. In otherembodiments, the multiwall nanotube includes three co-axially layeredtubes, in which the innermost tube (first tube) and the second tubesurrounding the innermost tube are made of different materials from eachother, and the third tube surrounding the second tube is made of thesame material as or different material from the innermost tube or thesecond tube.

In some embodiments, the multiwall nanotube includes four co-axiallylayered tubes each made of different materials A, B or C. In someembodiments, the materials of the four layers are from the innermost(first) tube to the fourth tube, A/B/A/A, AB/AB, AB/A/C, A/B/B/A, A/BBB,A/B/B/C, AB/C/A, A/B/C/B, or A/B/C/C.

In some embodiments, all the tubes of the multiwall nanotube arecrystalline nanotubes. In other embodiments, one or more tubes are anon-crystalline (e.g., amorphous) layer wrapping around the one or moreinner tubes. In some embodiments, the outermost tube is made of, forexample, a layer of HfO₂, Al₂O₃, ZrO₂, Y₂O₃, La₂O₃, B₄C, YN, Si₃N₄, BN,NbN, RuNb, YF₃, TiN, ZrN, Ru, Nb, Y, Sc, Ni, Mo, W, Pt, or Bi. In someembodiments, the outermost layer is made of the same material as thethird cover layer 540.

In some embodiments, a diameter of the innermost nanotube is in a rangefrom about 0.5 nm to about 20 nm and is in a range from about 1 nm toabout 10 nm in other embodiments. In some embodiments, a diameter of themultiwall nanotubes (i.e., diameter of the outermost tube) is in a rangefrom about 3 nm to about 40 nm and is in a range from about 5 nm toabout 20 nm in other embodiments. In some embodiments, a length of themultiwall nanotube is in a range from about 0.5 μm to about 50 μm and isin a range from about 1.0 μm to about 20 μm in other embodiments.

FIGS. 8A, 8B and 8C show various views of network membranes for a debriscatcher in accordance with embodiments of the present disclosure.

In some embodiments, the network membrane 550 includes a plurality ofmultiwall nanotubes 560. In some embodiments, the plurality of multiwallnanotubes are randomly arranged to form a network structure. In someembodiments, the plurality of multiwall nanotubes include only one typeof multiwall nanotubes in terms of material and structure (number oflayers). In other embodiments, the plurality of multiwall nanotubesinclude two or more types of multiwall nanotubes in terms of materialand structure (number of layers). For example, the plurality ofmultiwall nanotubes include a first type of multiwall nanotubes, e.g.,two wall nanotubes, and a second type of multiwall nanotubes, e.g.,three wall nanotubes; a first type of multiwall nanotubes, e.g., twowall nanotubes of layer A and layer B, and a second type of multiwallnanotubes, e.g., two wall nanotubes of layer A and layer C.

In some embodiments, the main network layer 550 includes a plurality ofone or more types of multiwall nanotubes 560, and a plurality of one ormore types of single wall nanotubes 511, as shown in FIG. 8B. In someembodiments, an amount (weight) of the single wall nanotubes 511 issmaller than an amount of the multiwall nanotubes 560. In someembodiments, an amount (weight) of the single wall nanotubes 511 isgreater than an amount of the multiwall nanotubes 560. In someembodiments, the amount (weight) of the multiwall nanotubes 560 is atleast about 20 wt % with respect to a total weight of the networkmembrane 550, or is at least 40 wt % in other embodiments. When theamount of the multiwall nanotubes is smaller than these ranges,sufficient strength of the network membrane may not be obtained.

In some embodiments, the main network membrane 550 includes a pluralityof multiwall nanotubes 560 and a plurality of flakes 521 (nano-flakes)made of a two-dimensional material in which one or more two-dimensionallayers are stacked, as shown in FIG. 8C. In some embodiments, an amount(weight) of the two-dimensional material flakes 521 is in a range fromabout 5 wt % to about 30 wt % with respect to a total weight of thenetwork membrane 100, and is in a range from about 10 wt % to about 20wt % in other embodiments.

FIG. 9A shows a manufacturing process of a network membrane, FIG. 9Bshows a flow chart thereof and FIG. 9C show manufacturing processes of anetwork membrane in accordance with an embodiment of the presentdisclosure.

In some embodiments, nanotubes are dispersed in a solution as shown inFIG. 9A. In some embodiments, the solution includes a solvent, such aswater, and a surfactant, such as sodium dodecyl sulfate (SDS). Thenanotubes are one type or two or more types of nanotubes (materialand/or wall numbers). In some embodiments, the nanotubes are single wallnanotubes. In some embodiments, single wall nanotubes are carbonnanotubes formed by various methods, such as arc-discharge, laserablation or chemical vapor deposition (CVD) methods. Similarly, singlewall BN nanotubes and single wall TMD nanotubes are also formed by a CVDprocess.

As shown in FIG. 9A, a support membrane is placed between a chamber or acylinder in which the nanotube dispersed solution is disposed and avacuum chamber. In some embodiments, the support membrane is an organicor inorganic porous or mesh material. In some embodiments, the supportmembrane is woven or non-woven fabric. In some embodiments, the supportmembrane has a circular shape.

As shown in FIG. 9A, the pressure in the vacuum chamber is reduced sothat a pressure is applied to the solvent in the chamber or cylinder.Since the mesh or pore size of the support membrane is sufficientlysmaller than the size of the nanotubes, the nanotubes are captured bythe support membrane while the solvent passes through the supportmembrane. The support membrane on which the nanotubes are deposited isdetached from the filtration apparatus of FIG. 9A and then is dried. Insome embodiments, the deposition by filtration is repeated so as toobtain a desired thickness of the nanotube network layer as shown inFIG. 9B. In some embodiments, after the deposition of the nanotubes inthe solution, other nanotubes are dispersed in the same or new solutionand the filter-deposition is repeated. In other embodiments, after thenanotubes are dried, another filter-deposition is performed. In therepetition, the same type of nanotubes is used in some embodiments, anddifferent types of nanotubes are used in other embodiments.

In some embodiments, the nanotubes dispersed in the solution includemultiwall nanotubes. In some embodiments, multiwall nanotubes are formedby CVD by using single wall nanotubes as seeds. In some embodiments,single wall nanotubes, such as carbon nanotubes, BN nanotubes or TMDnanotubes formed by CVD are placed over a substrate. Then, sourcematerials, such as source gases, are provided over the substrate withthe seed nanotubes. In a case of CVD for forming a MoS₂ layer, a Mo(CO)₆gas, a MoCl₅ gas, and/or a MoOCl₄ gas are used as a Mo source, and a H₂Sgas and/or a dimethylsulfide gas are used as a S source, in someembodiments. In other embodiments, a MoO₃ gas sublimed from a solid MoO₃or a MoCl₅ source and/or S gas sublimed from a solid S source can beused. Solid sources of Mo and S are placed in a reaction chamber and acarrier gas containing inert gas, such as Ar, N₂ and/or He flows in thereaction chamber. The solid sources are heated to generate gaseoussources by sublimation, and the generated gaseous sources react to formMoS₂ molecules. The MoS₂ molecules are then deposited around the seednanotubes over the substrate. The substrate is appropriately heated insome embodiments. In other embodiments, the entire reaction chamber isheated by induction heating. Other TMD layers can also be formed by CVDusing suitable source gases. For example, metal oxides, such as WO₃,PdO₂ and PtO₂ can be used as a sublimation source for W, Pd and Pt,respectively, and metal compounds, such as W(CO)₆, WF₆, WOCl₄, PtCl₂ andPdCl₂ can also be used as a metal source.

In other embodiments, the seed nanotubes are immersed in, dispersed inor treated by, one or more metal precursor, such as (NH₄)WS₄, W₀₃,(NH₄)MoS₄ or MoO₃ and placed over the substrate, and then a sulfur gasis provided over the substrate to form multiwall nanotubes.

In other embodiments, a carbon source gas is used to form a carbonnanotube as an outer layer over a BN or TMD inner nanotube. Three ormore co-axial nanotubes are formed by repeating above processes in someembodiments. In some embodiments, multiwall nanotubes are disposed inthe solution as shown in FIG. 9A. In some embodiments, a mixture ofsingle wall nanotubes and multiwall nanotubes are disposed in thesolution.

In some embodiments, when the main network membrane 550 includesnanotubes and two-dimensional material flakes, the deposition byfiltration for nanotubes and the deposition by filtration for the flakesare repeated as shown in FIG. 9C. In some embodiments, a mixture ofnanotubes and flakes are dispersed in the solvent, and the deposition byfiltration is performed to form a mixed network layer of nanotubes andtwo-dimensional material flakes.

Two-dimensional material layer(s) are formed over a substrate by a CVDmethod, and then the deposited layer is peeled off from the substrate.After the two-dimensional material layer is peeled off, the layer iscrushed into flakes in some embodiments.

FIGS. 10A and 10B to 13A and 13B show cross sectional views (the “A”figures) and plan (top) views (the “B” figures) of the various stagesfor manufacturing a debris catcher in accordance with an embodiment ofthe present disclosure. It is understood that additional operations canbe provided before, during, and after the processes shown by FIGS.10A-13B, and some of the operations described below can be replaced oreliminated, for additional embodiments of the method. The order of theoperations/processes may be interchangeable. Materials, configurations,methods, processes and/or dimensions as explained with respect to theforegoing embodiments are applicable to the following embodiments, andthe detailed description thereof may be omitted.

As shown in FIGS. 9A-9C, a nanotube layer 550L is formed on a supportmembrane 80 by deposition by filtering. As set forth above, the nanotubelayer 550L include single wall nanotubes, multiwall nanotubes and/or 2Dflakes. The nanotube layer 550L is then detached from a depositionapparatus, as shown in FIGS. 10A and 10B.

Then, as shown in FIGS. 11A and 11B, a frame 555 is attached to thenanotube layer 550L. In some embodiments, as shown in FIG. 9B, thesupport frame 15 has a circular ring or frame shape, but may have othershapes as shown in FIGS. 4C-4E.

Next, as shown in FIGS. 12A and 12B, the nanotube layer 550L and thesupport membrane 80 are cut to form a network membrane 550 having aframe 555, and then the support substrate 80 is detached or removed, insome embodiments. When the support substrate 80 is made of an organicmaterial, the support substrate 80 is removed by wet etching using anorganic solvent.

In some embodiments, when the nanotube layer 550L includes only singlewall nanotubes, one or more outer tubes are formed around each of thesingle wall nanotubes, as shown in FIGS. 13A and 13B. In someembodiments, a CVD process is performed using the single wall nanotubesas a seed. The CVD process is repeated a desired number of times to formthree or more outer tubes. In some embodiments, a cover layer similar tothe first, second or third cover layers as set forth above are formed toseal the network membrane 550 or the network membrane having multiwallnanotubes 560 together with the frame 555. In some embodiments, thecover layer is formed on only one main surface of the network membrane550 or the network membrane having multiwall nanotubes 560.

FIGS. 14A and 14B to 19A and 19B show cross sectional views (the “A”figures) and plan (top) views (the “B” figures) of the various stagesfor manufacturing a debris catcher mask in accordance with an embodimentof the present disclosure. It is understood that additional operationscan be provided before, during, and after the processes shown by FIGS.14A-19B, and some of the operations described below can be replaced oreliminated, for additional embodiments of the method. The order of theoperations/processes may be interchangeable. Materials, configurations,methods, processes and/or dimensions as explained with respect to theforegoing embodiments are applicable to the following embodiments, andthe detailed description thereof may be omitted.

As shown in FIGS. 9A-9C, a main network membrane 550L is formed on asupport membrane 80 by deposition by filtering. As set forth above, thenanotube layer 550L include single wall nanotubes, multiwall nanotubesand/or 2D flakes. The main network membrane 500L is then detached from adeposition apparatus, as shown in FIGS. 14A and 14B. Then, as shown inFIGS. 15A and 15B, a first cover layer 520 is formed over the mainnetwork membrane 550L in some embodiments.

The first cover layer 520, which is a two-dimensional material, isformed by, for example, a CVD method on a substrate, and then thedeposited two-dimensional layer(s) is peeled off from the substrate. Thepeeled two-dimensional layer(s) is subsequently transferred over themain network layer 550L formed on the support substrate 80, as shown inFIGS. 15A and 15B.

Then, as shown in FIGS. 16A and 16B, a frame 555 is attached to thefirst cover layer 520. In some embodiments, as shown in FIG. 16B, theframe 15 has a rectangular (including square) frame shape, and any othershape as shown in FIGS. 4B-4E can be used.

Next, as shown in FIGS. 17A and 17B, the first cover layer 520, the mainnetwork membrane 550L and the support membrane 80 are cut into arectangular shape to form a network membrane 550 having the frame 555,and then the support substrate 80 is detached or removed, in someembodiments. When the support substrate 80 is made of an organicmaterial, the support substrate 80 is removed by wet etching using anorganic solvent.

Further, as shown in FIGS. 18A and 18B, a second cover layer 530 isformed over the network membrane 550. The operations for forming thesecond cover layer 530, which is a two-dimensional material, is the sameas or similar to those for the first cover layer 520 as set forth above.In some embodiments, the first cover layer 520 and the second coverlayer 530 are sealed at the periphery thereof to fully encapsulate themain network membrane 550.

Further, as shown in FIGS. 19A and 19B, a third cover layer 540 isoptionally formed over the first cover layer 520, the second cover layer530 and the support frame 555. In some embodiments, the third coverlayer 540 is formed by CVD, physical vapor deposition (PVD) or atomiclayer deposition (ALD).

FIG. 20A and FIG. 20B illustrate a computer system 350 for controllingthe EUV exposure system 10 including the debris catcher 500 and itscomponents in accordance with various embodiments of the presentdisclosure. FIG. 20A is a schematic view of a computer system 350 thatcontrols the system 10 including the debris catcher 500 of FIGS. 1A-1C,2 and 3A-3C. In some embodiments, the computer system 350 is programmedto initiate a process for switching the slots/frames as shown in FIGS.3A-3C according to information from one or more sensors provided to theEUV exposure system.

As shown in FIG. 20A, the computer system 350 is provided with acomputer 1001 including an optical disk read only memory (e.g., CD-ROMor DVD-ROM) drive 1005 and a magnetic disk drive 1006, a keyboard 1002,a mouse 1003 (or other similar input device), and a monitor 10504.

FIG. 20B is a diagram showing an internal configuration of the computersystem 350. In FIG. 20B, the computer 1001 is provided with, in additionto the optical disk drive 1005 and the magnetic disk drive 1006, one ormore processors 1011, such as a micro-processor unit (MPU) or a centralprocessing unit (CPU); a read-only memory (ROM) 1012 in which a programsuch as a boot up program is stored; a random access memory (RAM) 1013that is connected to the processors 1011 and in which a command of anapplication program is temporarily stored, and a temporary electronicstorage area is provided; a hard disk 1014 in which an applicationprogram, an operating system program, and data are stored; and a datacommunication bus 1015 that connects the processors 1011, the ROM 1012,and the like. Note that the computer 1001 may include a network card(not shown) for providing a connection to a computer network such as alocal area network (LAN), wide area network (WAN) or any other usefulcomputer network for communicating data used by the computer system 350and the EUV exposure system 10. In various embodiments, the controller350 communicates via wireless or hardwired connection to the EUVexposure system 10 and its components.

The program for causing the computer system 350 to execute the processfor controlling the debris catcher 500 of FIGS. 2 and 3A-3C to executeswitching the slots/frames as set forth above according to theembodiments disclosed herein are stored in an optical disk 1021 or amagnetic disk 1022, which is inserted into the optical disk drive 1005or the magnetic disk drive 1006, and transmitted to the hard disk 1014.Alternatively, the program is transmitted via a network (not shown) tothe computer system 350 and stored in the hard disk 1014. At the time ofexecution, the program is loaded into the RAM 1013. The program isloaded from the optical disk 1021 or the magnetic disk 1022, or directlyfrom a network in various embodiments.

The stored programs do not necessarily have to include, for example, anoperating system (OS) or a third party program to cause the computer1001 to execute the methods disclosed herein. The program may onlyinclude a command portion to call an appropriate function (module) in acontrolled mode and obtain desired results in some embodiments. Invarious embodiments described herein, the controller 1050 is incommunication with the EUV exposure system 10 to control variousfunctions thereof.

The controller 350 is coupled to the EUV exposure system 10 includingthe debris catcher 500 in various embodiments. The controller 350 isconfigured to provide control data to those system components andreceive process and/or status data from those system components. Forexample, the controller 350 comprises a microprocessor, a memory (e.g.,volatile or non-volatile memory), and a digital I/O port capable ofgenerating control voltages sufficient to communicate and activateinputs to the processing system, as well as monitor outputs from the EUVexposure system 10. In addition, a program stored in the memory isutilized to control the aforementioned components of the EUV exposuresystem 10 according to a process recipe. Furthermore, the controller 350is configured to analyze the process and/or status data, to compare theprocess and/or status data with target process and/or status data, andto use the comparison to change a process and/or control a systemcomponent. In addition, the controller 350 is configured to analyze theprocess and/or status data, to compare the process and/or status datawith historical process and/or status data, and to use the comparison topredict, prevent, and/or declare a fault or alarm.

As set forth above, the executed program causes the processor orcomputer to switch one slot or frame having the network membrane toanother slot or frame having the network membrane according todegradation degree of the network membrane 550. In some embodiments, thedegradation degree is determined by the time duration for which thenetwork membrane is used. In some embodiments, the executed programcauses the processor or computer to issue a switching signalperiodically, for example, every day, week or month. In otherembodiments, the switching signal is provided every certain number ofpulses of the excitation laser. In some embodiments, the switchingsignal is provided when an intensity of the EUV radiation in the scannerside (or in the LPP radiation side) decreased below a threshold. In someembodiments, a weight monitor 411 (see, FIG. 2 ) is provided inside ornear the lower cone 400 to monitor a weight of the accumulated Sn, andwhen the amount of Sn exceeds a threshold, the switching signal isprovided. In some embodiments, the EUV intensity is measured at thescanner side when the currently used network membrane is used and whenthe empty slot (through opening) is used, and when the difference in theintensities is greater than a threshold, a new network membrane is usedby rotating the debris catcher as shown in FIGS. 3A and 3B or by slidingthe debris catcher as shown in FIG. 3C.

In accordance with the foregoing, improved debris mitigation is achievedin order to prevent mask fall-on defects and the like in a semiconductormanufacturing process. Taking advantages of the off period of the EUVlight pulse generation cycle, a debris catcher is provided at theinterface between the source and scanner chambers to pass a substantialamount of EUV light beam and block tin debris (e.g. nanoparticledebris). In such a manner, an operation period (time between maintenanceoperations) of the EUV radiation system can be prolonged from about amonth (without a debris catcher) to about 6 months with the debriscatcher.

According to various embodiments, an EUV lithography apparatus includesa light source that generates an EUV light beam, a scanner that receivesthe light from a junction with the light source and directs the light toa reticle stage, and a debris catcher disposed on a EUV beam pathbetween the light source and the scanner. The debris catcher includes anetwork membrane including a plurality of nano-fibers. In one or more ofthe foregoing or following embodiments, the plurality of nano-fibersinclude a plurality of carbon nanotubes. In one or more of the foregoingor following embodiments, the plurality of nano-fibers include aplurality of nanotubes of a transition metal dichalcogenide. In one ormore of the foregoing or following embodiments, the plurality ofnano-fibers include a plurality of co-axial nanotubes, each of whichincludes an inner tube and one or more outer tubes surrounding the innertube. In one or more of the foregoing or following embodiments, two ofthe inner tube and one or more outer tubes are made of differentmaterials from each other. In one or more of the foregoing or followingembodiments, each of the inner tube and the one or more outer tubes isone selected from the group consisting of a carbon nanotube, a boronnitride nanotube, a transition metal dichalcogenide (TMD) nanotube,where TMD is represented by MX₂, where M is one or more of Mo, W, Pd,Pt, or Hf, and X is one or more of S, Se or Te. In one or more of theforegoing or following embodiments, the inner tube is a carbon nanotube.In one or more of the foregoing or following embodiments, the debriscatcher further includes a first layer and a second layer, and thenetwork membrane is disposed between the first layer and second layer.In one or more of the foregoing or following embodiments, the firstlayer includes a first two-dimensional material and the second layerincludes a second two-dimensional material. In one or more of theforegoing or following embodiments, each of the first and secondtwo-dimensional materials includes at least one selected from the groupconsisting of boron nitride (BN), graphene, MoS₂, MoSe₂, WS₂, and WSe₂.In one or more of the foregoing or following embodiments, wherein thefirst two-dimensional material is different from the secondtwo-dimensional material.

In accordance with another aspect of the present disclosure, an EUVlithography apparatus includes a light source that generates an EUVlight beam, a scanner that receives the light from a junction with thelight source and directs the light to a reticle stage, and a debriscatcher disposed on a EUV beam path between the light source and thescanner. The debris catcher comprises a plurality of slots or frames,and at least two of the plurality of slots or frames include a networkmembrane including a plurality of nano-fibers. In one or more of theforegoing or following embodiments, the EUV lithography apparatusfurther includes a controller configured to switch from one slot orframe of the debris catcher having the network membrane to another slotor frame of the debris catcher having the network membrane according todegradation of the network membrane of the one slot or frame. In one ormore of the foregoing or following embodiments, the debris catcherincludes a revolver plate rotatable around a rotational axis and theplurality of slots are provided to the revolver plate. In one or more ofthe foregoing or following embodiments, the debris catcher comprises theplurality of frames, a rotatable mechanism and an arm connecting therotatable mechanism and each of the plurality of frames. In one or moreof the foregoing or following embodiments, the debris catcher comprisesa slidable plate and the plurality of slots are provided to the slidableplate. In one or more of the foregoing or following embodiments, whereinone of the plurality of slots or frame has no network membrane. In oneor more of the foregoing or following embodiments, the plurality ofnano-fibers include a plurality of carbon nanotubes or a plurality ofnanotubes of a transition metal dichalcogenide.

In accordance with another aspect of the present disclosure, in a methodof operating an EUV lithography apparatus, the EUV lithography apparatusincludes a light source that generates an EUV light beam and a scannerthat receives the light from a junction with the light source anddirects the light to a reticle stage. In the method, a debris catcher isprovided on a EUV beam path between the light source and the scanner,and the tin debris generated in the light source is collected by thedebris catcher. The debris catcher includes a plurality of slots orframes, and at least two of the plurality of slots or frames include anetwork membrane including a plurality of nano-fibers. In one or more ofthe foregoing or following embodiments, the plurality of nano-fibersinclude a plurality of carbon nanotubes or a plurality of nanotubes of atransition metal dichalcogenide. In one or more of the foregoing orfollowing embodiments, one slot or frame of the debris catcher havingthe network membrane is switched to another slot or frame of the debriscatcher having the network membrane according to degradation of thenetwork membrane of the one slot or frame.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. An extreme ultra violet (EUV) lithographyapparatus, comprising: a light source that generates an EUV light beam;a scanner that receives the light from a junction with the light sourceand directs the light to a reticle stage; and a debris catcher disposedon a EUV beam path between the light source and the scanner, wherein thedebris catcher comprises a network membrane including a plurality ofnano-fibers.
 2. The EUV lithography apparatus of claim 1, wherein theplurality of nano-fibers include a plurality of carbon nanotubes.
 3. TheEUV lithography apparatus of claim 1, wherein the plurality ofnano-fibers include a plurality of nanotubes of a transition metaldichalcogenide.
 3. The EUV lithography apparatus of claim 1, wherein theplurality of nano-fibers include a plurality of co-axial nanotubes, eachof which includes an inner tube and one or more outer tubes surroundingthe inner tube.
 4. The EUV lithography apparatus of claim 3, wherein theinner tube and one or more outer tubes are made of different materialsfrom each other.
 5. The EUV lithography apparatus of claim 4, whereineach of the inner tube and the one or more outer tubes is one selectedfrom the group consisting of a carbon nanotube, a boron nitridenanotube, a transition metal dichalcogenide (TMD) nanotube, where TMD isrepresented by MX₂, where M is one or more of Mo, W, Pd, Pt, or Hf, andX is one or more of S, Se or Te.
 6. The EUV lithography apparatus ofclaim 5, wherein the inner tube is a carbon nanotube.
 7. The EUVlithography apparatus of claim 1, wherein the debris catcher furthercomprises: a first layer; and a second layer, wherein the networkmembrane is disposed between the first layer and second layer.
 8. TheEUV lithography apparatus of claim 7, wherein the first layer includes afirst two-dimensional material and the second layer includes a secondtwo-dimensional material.
 9. The EUV lithography apparatus of claim 8,wherein each of the first and second two-dimensional materials includesat least one selected from the group consisting of boron nitride (BN),graphene, MoS₂, MoSe₂, WS₂, and WSe₂.
 10. The EUV lithography apparatusof claim 9, wherein the first two-dimensional material is different fromthe second two-dimensional material.
 11. An extreme ultra violet (EUV)lithography apparatus, comprising: a light source that generates an EUVlight beam; a scanner that receives the light from a junction with thelight source and directs the light to a reticle stage; and a debriscatcher disposed on a EUV beam path between the light source and thescanner, wherein the debris catcher comprises a plurality of slots orframes, and at least two of the plurality of slots or frames include anetwork membrane including a plurality of nano-fibers.
 12. The EUVlithography apparatus of claim 11, further comprising a controllerconfigured to switch from one slot or frame of the debris catcher havingthe network membrane to another slot or frame of the debris catcherhaving the network membrane according to degradation of the networkmembrane of the one slot or frame.
 13. The EUV lithography apparatus ofclaim 12, wherein the debris catcher comprises a revolver platerotatable around a rotational axis and the plurality of slots areprovided in the revolver plate.
 14. The EUV lithography apparatus ofclaim 12, wherein the debris catcher comprises the plurality of frames,a rotatable mechanism and an arm connecting the rotatable mechanism andeach of the plurality of frames.
 15. The EUV lithography apparatus ofclaim 12, wherein the debris catcher comprises a slidable plate and theplurality of slots are provided in the slidable plate.
 16. The EUVlithography apparatus of claim 11, wherein one of the plurality of slotsor frame has no network membrane.
 17. The EUV lithography apparatus ofclaim 11, wherein the plurality of nano-fibers include a plurality ofcarbon nanotubes or a plurality of nanotubes of a transition metaldichalcogenide.
 18. A method of operating an extreme ultra violet (EUV)lithography apparatus comprising a light source that generates an EUVlight beam and a scanner that receives the light from a junction withthe light source and directs the light to a reticle stage, the methodcomprising: providing a debris catcher on a EUV beam path between thelight source and the scanner; and collecting by the debris catcher tindebris generated in the light source, wherein the debris catchercomprises a plurality of slots or frames, and at least two of theplurality of slots or frames include a network membrane including aplurality of nano-fibers.
 19. The method of claim 18, wherein theplurality of nano-fibers include a plurality of carbon nanotubes or aplurality of nanotubes of a transition metal dichalcogenide.
 20. Themethod of claim 19, further comprising switching from one slot or frameof the debris catcher having the network membrane to another slot orframe of the debris catcher having the network membrane according todegradation of the network membrane of the one slot or frame.